Many engines, transmissions and other mechanical devices use headless bolts or studs for assembly of related components. As used herein, the term "stud" or "headless bolt" refers generally to a shaft having screw threads formed along part or all of its entire length. When assembling components of an engine during production or after repair, studs must be installed without damaging the threads. The insertion of these studs is often a difficult, tedious and very expensive task. One makeshift method commonly used is to "double nut" a stud by threading two nuts onto the stud to be inserted, and tightening each nut against the other in opposite directions until they abut and fixedly lock onto the stud. The assembled double nut and stud combination then is inserted into the required mechanical device using the double nuts as a means for driving the assembled combination. After the stud is mounted, the nuts must be loosened by rotating each in opposite directions and then backed off from the mounted stud. This cumbersome and time consuming method is eliminated by forms of stud insertion tools.
However, in the past many stud driving and insertion tools were complex, either requiring many individual pieces, or were of a design which required considerable amount of effort and physical manipulation in mounting the headless bolt or stud into the associated mechanical device. Many of these tools were very expensive to manufacture because of the large number and intricacy of the individual components.
Accordingly, a principal object of the present invention is to provide a stud insertion device or tool which is of simple construction, efficient in use, and comparatively inexpensive to manufacture.
Previous stud installing tools required use of an independent locking device such as a pin or set screw to first lock the stud into the tool before installation of the stud into the associated member. When these forms of prior devices are utilized, the stud, after being driven and mounted into the desired location, must then be unlocked and the tool backed off from the stud while taking care not to loosen the stud from its mounted location. The present invention is designed to install studs into a device and then, release itself with a minimal amount of additional motion and effort.
The present invention requires no moveable locking component to mount or release the stud from the main socket body of the tool. In accordance with the present invention, a stop and release projection is formed as part of a main socket body at the end of a threaded axially bored hole. Any thread design may be utilized in the axially bored hole. This projection may be configured in many different shapes, but preferably may be an arcuate projection such as formed by a ball bearing, or, as depicted in a preferred embodiment, may be a cylindrically shaped projection with a chamfered end. These projections work equally well on round, flat or sunken end studs so long as the abutting surface area between the projection and the stud is less than the entire surface area of the tool abutting end of the stud. This allows the tool to be easily removed from the stud after mounting in the desired location. Furthermore, the present invention utilizes this projection to provide the main driving force to be directed at the center of the associated stud so that the stud is driven straight and is not bent during mounting into the desired location. The pressure created between the stud and the tool will be firm enough to assist in firmly driving and mounting the stud into the required device, but will not restrict the stud's release from the tool socket thereafter.
Other prior stud-mounting tools utilize locking rings or collars with threaded pitches different than the pitch of the stud. This difference would cause the ring or collar to "jam" onto the stud and thereby, catch and engage the stud. After insertion, the device must be reversed to "un-jam" and remove the device from the mounted stud, and, because of the difference in thread pitch, excessive wear of the stud threads was created.
For example, U.S. Pat. No. 1,438,269 issued to Sehrt, utilizes a sleeve threaded at one end to receive a stud, and the sleeve also is threaded at the other end to receive a cap screw. The cap screw has a greater pitch than the stud. A pin is driven radially through the shaft of the cap screw. Lugs are mounted to the top of the sleeve to enable the sleeve to be rotated when the cap screw is turned to bring the pins into contact with the lugs. Unlike the present invention, Sehrt utilizes a separate sleeve and cap screw to hold and drive the stud.
U.S. Pat. No. 3,292,469 issued to McKean, utilizes a bushing having external multiple threads which are threaded to receive the bushing in a blind hole, and an internal thread to receive the stud. McKean utilizes resilient O-rings to bind and help resist binding upon release of the stud during removal of the stud from the tool once the stud is mounted. The present invention utilizes a totally different means of grasping the stud and locking it into the tool for mounting.
U.S. Pat. No. 2,521,910 issued to Goldberg, utilizes a sleeve with an internally threaded bore formed with three arcuate evenly spaced corroborating die cutting teeth, the same being separated by slots or notches extending the full length of the tool, whereby a headless bolt or screw is threaded by hand into the threaded bore. A pin is radially inserted through selected holes in the sleeve to contact the stud. After the stud is driven, the pin is removed, thus releasing the stud. The present invention is distinct from Goldberg in that it is not a multiple component device with specially cut threads and further does not require a removable pin.
U.S. Pat. No. 2,746,328 issued to Valvano, utilizes a locking pin that is threaded through the cylindrical wall of the tool to lock a jaw set against the stud. The present invention does not utilize pins or jaw sets to lock the stud into the tool before mounting.
The present invention provides many advantages over previous stud installation tools in that it allows for easy insertion of a stud into the tool, then easily mounts the stud into the required device, after which, upon a single action of reverse rotation, allows the mounted stud to be loosened from the tool without appreciably loosening the already mounted stud from the required device, thus allowing the tool to be very quickly backed off from the mounted stud.
An additional advantage is that the present invention is very compact in design, allowing the tool to be used in tight places where many other tools would require greater clearance to operate.
Numerous other advantages and features of the invention will become readily apparent from the following detailed description of the preferred embodiment of the invention, from the claims and from the accompanying drawings in which like numerals are employed to designate like parts throughout.